Initial revision

4 files changed, 2483 insertions, 0 deletions

diff --git a/sys/net/if_ppp.c b/sys/net/if_ppp.c
new file mode 100644
index 0000000..e484e22
--- /dev/null
+++ b/sys/net/if_ppp.c
@@ -0,0 +1,1575 @@
+/*
+ * if_ppp.c - Point-to-Point Protocol (PPP) Asynchronous driver.
+ *
+ * Copyright (c) 1989 Carnegie Mellon University.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms are permitted
+ * provided that the above copyright notice and this paragraph are
+ * duplicated in all such forms and that any documentation,
+ * advertising materials, and other materials related to such
+ * distribution and use acknowledge that the software was developed
+ * by Carnegie Mellon University.  The name of the
+ * University may not be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * Drew D. Perkins
+ * Carnegie Mellon University
+ * 4910 Forbes Ave.
+ * Pittsburgh, PA 15213
+ * (412) 268-8576
+ * ddp@andrew.cmu.edu
+ *
+ * Based on:
+ *	@(#)if_sl.c	7.6.1.2 (Berkeley) 2/15/89
+ *
+ * Copyright (c) 1987 Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms are permitted
+ * provided that the above copyright notice and this paragraph are
+ * duplicated in all such forms and that any documentation,
+ * advertising materials, and other materials related to such
+ * distribution and use acknowledge that the software was developed
+ * by the University of California, Berkeley.  The name of the
+ * University may not be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * Serial Line interface
+ *
+ * Rick Adams
+ * Center for Seismic Studies
+ * 1300 N 17th Street, Suite 1450
+ * Arlington, Virginia 22209
+ * (703)276-7900
+ * rick@seismo.ARPA
+ * seismo!rick
+ *
+ * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
+ * Converted to 4.3BSD Beta by Chris Torek.
+ * Other changes made at Berkeley, based in part on code by Kirk Smith.
+ *
+ * Converted to 4.3BSD+ 386BSD by Brad Parker (brad@cayman.com)
+ * Added VJ tcp header compression; more unified ioctls
+ *
+ * Extensively modified by Paul Mackerras (paulus@cs.anu.edu.au).
+ * Cleaned up a lot of the mbuf-related code to fix bugs that
+ * caused system crashes and packet corruption.  Changed pppstart
+ * so that it doesn't just give up with a collision if the whole
+ * packet doesn't fit in the output ring buffer.
+ *
+ * Added priority queueing for interactive IP packets, following
+ * the model of if_sl.c, plus hooks for bpf.
+ * Paul Mackerras (paulus@cs.anu.edu.au).
+ */
+
+/* $Id: if_ppp.c,v 1.7 1994/01/25 05:56:06 deraadt Exp paulus $ */
+/* from if_sl.c,v 1.11 84/10/04 12:54:47 rick Exp */
+
+#include "ppp.h"
+#if NPPP > 0
+
+#define VJC
+
+#include <sys/param.h>
+#include <sys/proc.h>
+#include <sys/mbuf.h>
+#include <sys/buf.h>
+#include <sys/dkstat.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <sys/file.h>
+#include <sys/tty.h>
+#include <sys/kernel.h>
+#include <sys/conf.h>
+#include <sys/vnode.h>
+
+#include <net/if.h>
+#include <net/if_types.h>
+#include <net/netisr.h>
+#include <net/route.h>
+
+#if INET
+#include <netinet/in.h>
+#include <netinet/in_systm.h>
+#include <netinet/in_var.h>
+#include <netinet/ip.h>
+#endif
+
+#include "bpfilter.h"
+#if NBPFILTER > 0
+#include <sys/time.h>
+#include <net/bpf.h>
+#endif
+
+#ifdef VJC
+#include <net/slcompress.h>
+#define HDROFF	MAX_HDR
+/* HDROFF should really be 128, but other parts of the system will
+   panic on TCP+IP headers bigger than MAX_HDR = MHLEN (100). */
+
+#else
+#define	HDROFF	(0)
+#endif
+
+#include <net/if_ppp.h>
+#include <machine/cpu.h>
+
+/* This is a NetBSD-current kernel. */
+#define CCOUNT(q)	((q)->c_cc)
+
+#define	PPP_HIWAT	400	/* Don't start a new packet if HIWAT on que */
+
+struct ppp_softc ppp_softc[NPPP];
+
+void	pppattach __P((void));
+int	pppopen __P((dev_t dev, struct tty *tp));
+void	pppclose __P((struct tty *tp, int flag));
+int	pppread __P((struct tty *tp, struct uio *uio, int flag));
+int	pppwrite __P((struct tty *tp, struct uio *uio, int flag));
+int	ppptioctl __P((struct tty *tp, int cmd, caddr_t data, int flag,
+		       struct proc *));
+int	pppoutput __P((struct ifnet *ifp, struct mbuf *m0,
+		       struct sockaddr *dst));
+void	pppinput __P((int c, struct tty *tp));
+int	pppioctl __P((struct ifnet *ifp, int cmd, caddr_t data));
+void	pppstart __P((struct tty *tp));
+
+static int	pppasyncstart __P((struct ppp_softc *));
+static u_short	pppfcs __P((u_short fcs, u_char *cp, int len));
+static int	pppgetm __P((struct ppp_softc *sc));
+static struct	mbuf *ppp_btom __P((struct ppp_softc *sc));
+static void	pppdumpm __P((struct mbuf *m0, int pktlen));
+static void	pppdumpb __P((u_char *b, int l));
+static void	ppplogchar __P((struct ppp_softc *, int));
+
+/*
+ * Some useful mbuf macros not in mbuf.h.
+ */
+#define M_DATASTART(m)	\
+	((m)->m_flags & M_EXT ? (m)->m_ext.ext_buf : \
+	    (m)->m_flags & M_PKTHDR ? (m)->m_pktdat : (m)->m_dat)
+
+#define M_DATASIZE(m)	\
+	((m)->m_flags & M_EXT ? (m)->m_ext.ext_size : \
+	    (m)->m_flags & M_PKTHDR ? MHLEN: MLEN)
+
+/*
+ * The following disgusting hack gets around the problem that IP TOS
+ * can't be set yet.  We want to put "interactive" traffic on a high
+ * priority queue.  To decide if traffic is interactive, we check that
+ * a) it is TCP and b) one of its ports is telnet, rlogin or ftp control.
+ */
+static u_short interactive_ports[8] = {
+	0,	513,	0,	0,
+	0,	21,	0,	23,
+};
+#define INTERACTIVE(p) (interactive_ports[(p) & 7] == (p))
+
+/*
+ * Does c need to be escaped?
+ */
+#define ESCAPE_P(c)	(sc->sc_asyncmap[(c) >> 5] & (1 << ((c) & 0x1F)))
+
+/*
+ * Called from boot code to establish ppp interfaces.
+ */
+void
+pppattach()
+{
+    register struct ppp_softc *sc;
+    register int i = 0;
+
+    for (sc = ppp_softc; i < NPPP; sc++) {
+	sc->sc_if.if_name = "ppp";
+	sc->sc_if.if_unit = i++;
+	sc->sc_if.if_mtu = PPP_MTU;
+	sc->sc_if.if_flags = IFF_POINTOPOINT;
+	sc->sc_if.if_type = IFT_PPP;
+	sc->sc_if.if_hdrlen = PPP_HDRLEN;
+	sc->sc_if.if_ioctl = pppioctl;
+	sc->sc_if.if_output = pppoutput;
+	sc->sc_if.if_snd.ifq_maxlen = IFQ_MAXLEN;
+	sc->sc_inq.ifq_maxlen = IFQ_MAXLEN;
+	sc->sc_fastq.ifq_maxlen = IFQ_MAXLEN;
+	if_attach(&sc->sc_if);
+#if NBPFILTER > 0
+	bpfattach(&sc->sc_bpf, &sc->sc_if, DLT_PPP, PPP_HDRLEN);
+#endif
+    }
+}
+
+/*
+ * Allocate a ppp interface unit and initialize it.
+ */
+struct ppp_softc *
+pppalloc(pid)
+    pid_t pid;
+{
+    int nppp;
+    struct ppp_softc *sc;
+
+    for (nppp = 0, sc = ppp_softc; nppp < NPPP; nppp++, sc++)
+	if (sc->sc_xfer == pid) {
+	    sc->sc_xfer = 0;
+	    break;
+	}
+    if (nppp >= NPPP)
+	for (nppp = 0, sc = ppp_softc; nppp < NPPP; nppp++, sc++)
+	    if (sc->sc_devp == NULL)
+		break;
+    if (nppp >= NPPP)
+	return NULL;
+
+    sc->sc_flags = 0;
+    sc->sc_mru = PPP_MRU;
+#ifdef VJC
+    sl_compress_init(&sc->sc_comp);
+#endif
+    sc->sc_if.if_flags |= IFF_RUNNING;
+
+    return sc;
+}
+
+/*
+ * Deallocate a ppp unit.
+ */
+pppdealloc(sc)
+    struct ppp_softc *sc;
+{
+    struct mbuf *m;
+
+    if_down(&sc->sc_if);
+    sc->sc_devp = NULL;
+    sc->sc_xfer = 0;
+    for (;;) {
+	IF_DEQUEUE(&sc->sc_inq, m);
+	if (m == NULL)
+	    break;
+	m_freem(m);
+    }
+    for (;;) {
+	IF_DEQUEUE(&sc->sc_fastq, m);
+	if (m == NULL)
+	    break;
+	m_freem(m);
+    }
+    sc->sc_if.if_flags &= ~(IFF_UP|IFF_RUNNING);
+}
+    
+/*
+ * Line specific open routine for async tty devices.
+ * Attach the given tty to the first available ppp unit.
+ */
+/* ARGSUSED */
+int
+pppopen(dev, tp)
+    dev_t dev;
+    register struct tty *tp;
+{
+    struct proc *p = curproc;		/* XXX */
+    register struct ppp_softc *sc;
+    int error, s, i;
+
+    if (error = suser(p->p_ucred, &p->p_acflag))
+	return (error);
+
+    if (tp->t_line == PPPDISC) {
+	sc = (struct ppp_softc *) tp->t_sc;
+	if (sc != NULL && sc->sc_devp == (void *) tp)
+	    return (0);
+    }
+
+    if ((sc = pppalloc(p->p_pid)) == NULL)
+	return ENXIO;
+
+    if (sc->sc_outm != NULL) {
+	m_freem(sc->sc_outm);
+	sc->sc_outm = NULL;
+    }
+	
+    if (pppgetm(sc) == 0) {
+	sc->sc_if.if_flags &= ~(IFF_UP|IFF_RUNNING);
+	return (ENOBUFS);
+    }
+
+    sc->sc_ilen = 0;
+    bzero(sc->sc_asyncmap, sizeof(sc->sc_asyncmap));
+    sc->sc_asyncmap[0] = 0xffffffff;
+    sc->sc_asyncmap[3] = 0x60000000;
+    sc->sc_rasyncmap = 0;
+    sc->sc_devp = (void *) tp;
+    sc->sc_start = pppasyncstart;
+
+    tp->t_sc = (caddr_t) sc;
+    ttyflush(tp, FREAD | FWRITE);
+
+    return (0);
+}
+
+/*
+ * Line specific close routine.
+ * Detach the tty from the ppp unit.
+ * Mimics part of ttyclose().
+ */
+void
+pppclose(tp, flag)
+    struct tty *tp;
+    int flag;
+{
+    register struct ppp_softc *sc;
+    struct mbuf *m;
+    int s;
+
+    ttywflush(tp);
+    s = splimp();		/* paranoid; splnet probably ok */
+    tp->t_line = 0;
+    sc = (struct ppp_softc *)tp->t_sc;
+    if (sc != NULL) {
+	tp->t_sc = NULL;
+	if (tp == (struct tty *) sc->sc_devp) {
+	    m_freem(sc->sc_outm);
+	    sc->sc_outm = NULL;
+	    m_freem(sc->sc_m);
+	    sc->sc_m = NULL;
+	    pppdealloc(sc);
+	}
+    }
+    splx(s);
+}
+
+/*
+ * Line specific (tty) read routine.
+ */
+int
+pppread(tp, uio, flag)
+    register struct tty *tp;
+    struct uio *uio;
+    int flag;
+{
+    register struct ppp_softc *sc = (struct ppp_softc *)tp->t_sc;
+    struct mbuf *m, *m0;
+    register int s;
+    int error = 0;
+
+    if ((tp->t_state & TS_CARR_ON) == 0 && (tp->t_cflag & CLOCAL) == 0)
+	return 0;		/* end of file */
+    if (sc == NULL || tp != (struct tty *) sc->sc_devp)
+	return 0;
+    s = splimp();
+    while (sc->sc_inq.ifq_head == NULL && tp->t_line == PPPDISC) {
+	if (tp->t_state & TS_ASYNC || flag & IO_NDELAY) {
+	    splx(s);
+	    return (EWOULDBLOCK);
+	}
+	error = ttysleep(tp, (caddr_t)&tp->t_rawq, TTIPRI|PCATCH, ttyin, 0);
+	if (error)
+	    return error;
+    }
+    if (tp->t_line != PPPDISC) {
+	splx(s);
+	return (-1);
+    }
+
+    /* Pull place-holder byte out of canonical queue */
+    getc(&tp->t_canq);
+
+    /* Get the packet from the input queue */
+    IF_DEQUEUE(&sc->sc_inq, m0);
+    splx(s);
+
+    for (m = m0; m && uio->uio_resid; m = m->m_next)
+	if (error = uiomove(mtod(m, u_char *), m->m_len, uio))
+	    break;
+    m_freem(m0);
+    return (error);
+}
+
+/*
+ * Line specific (tty) write routine.
+ */
+int
+pppwrite(tp, uio, flag)
+    register struct tty *tp;
+    struct uio *uio;
+    int flag;
+{
+    register struct ppp_softc *sc = (struct ppp_softc *)tp->t_sc;
+    struct mbuf *m, *m0, **mp;
+    struct sockaddr dst;
+    struct ppp_header *ph1, *ph2;
+    int len, error;
+
+    if ((tp->t_state & TS_CARR_ON) == 0 && (tp->t_cflag & CLOCAL) == 0)
+	return 0;		/* wrote 0 bytes */
+    if (tp->t_line != PPPDISC)
+	return (EINVAL);
+    if (sc == NULL || tp != (struct tty *) sc->sc_devp)
+	return EIO;
+    if (uio->uio_resid > sc->sc_if.if_mtu + PPP_HDRLEN ||
+	uio->uio_resid < PPP_HDRLEN)
+	return (EMSGSIZE);
+    for (mp = &m0; uio->uio_resid; mp = &m->m_next) {
+	MGET(m, M_WAIT, MT_DATA);
+	if ((*mp = m) == NULL) {
+	    m_freem(m0);
+	    return (ENOBUFS);
+	}
+	if (uio->uio_resid >= MCLBYTES / 2)
+	    MCLGET(m, M_DONTWAIT);
+	len = M_TRAILINGSPACE(m);
+	if (len > uio->uio_resid)
+	    len = uio->uio_resid;
+	if (error = uiomove(mtod(m, u_char *), len, uio)) {
+	    m_freem(m0);
+	    return (error);
+	}
+	m->m_len = len;
+    }
+    dst.sa_family = AF_UNSPEC;
+    ph1 = (struct ppp_header *) &dst.sa_data;
+    ph2 = mtod(m0, struct ppp_header *);
+    *ph1 = *ph2;
+    m0->m_data += PPP_HDRLEN;
+    m0->m_len -= PPP_HDRLEN;
+    return (pppoutput(&sc->sc_if, m0, &dst));
+}
+
+/*
+ * Line specific (tty) ioctl routine.
+ * Provide a way to get the ppp unit number.
+ * This discipline requires that tty device drivers call
+ * the line specific l_ioctl routine from their ioctl routines.
+ */
+/* ARGSUSED */
+int
+ppptioctl(tp, cmd, data, flag, p)
+    struct tty *tp;
+    caddr_t data;
+    int cmd, flag;
+    struct proc *p;
+{
+    register struct ppp_softc *sc = (struct ppp_softc *) tp->t_sc;
+    int s, error, flags, mru;
+
+    if (sc == NULL || tp != (struct tty *) sc->sc_devp)
+	return -1;
+
+    switch (cmd) {
+    case FIONREAD:
+	*(int *)data = sc->sc_inq.ifq_len;
+	break;
+
+    case PPPIOCGUNIT:
+	*(int *)data = sc->sc_if.if_unit;
+	break;
+
+    case PPPIOCGFLAGS:
+	*(u_int *)data = sc->sc_flags;
+	break;
+
+    case PPPIOCSFLAGS:
+	if (error = suser(p->p_ucred, &p->p_acflag))
+	    return (error);
+	flags = *(int *)data & SC_MASK;
+	s = splimp();
+	sc->sc_flags = (sc->sc_flags & ~SC_MASK) | flags;
+	splx(s);
+	break;
+
+    case PPPIOCSASYNCMAP:
+	if (error = suser(p->p_ucred, &p->p_acflag))
+	    return (error);
+	sc->sc_asyncmap[0] = *(u_int *)data;
+	break;
+
+    case PPPIOCGASYNCMAP:
+	*(u_int *)data = sc->sc_asyncmap[0];
+	break;
+
+    case PPPIOCSRASYNCMAP:
+	if (error = suser(p->p_ucred, &p->p_acflag))
+	    return (error);
+	sc->sc_rasyncmap = *(u_int *)data;
+	break;
+
+    case PPPIOCGRASYNCMAP:
+	*(u_int *)data = sc->sc_rasyncmap;
+	break;
+
+    case PPPIOCSXASYNCMAP:
+	if (error = suser(p->p_ucred, &p->p_acflag))
+	    return (error);
+	bcopy(data, sc->sc_asyncmap, sizeof(sc->sc_asyncmap));
+	sc->sc_asyncmap[1] = 0;		    /* mustn't escape 0x20 - 0x3f */
+	sc->sc_asyncmap[2] &= ~0x40000000;  /* mustn't escape 0x5e */
+	sc->sc_asyncmap[3] |= 0x60000000;   /* must escape 0x7d, 0x7e */
+	break;
+
+    case PPPIOCGXASYNCMAP:
+	bcopy(sc->sc_asyncmap, data, sizeof(sc->sc_asyncmap));
+	break;
+
+    case PPPIOCSMRU:
+	if (error = suser(p->p_ucred, &p->p_acflag))
+	    return (error);
+	mru = *(int *)data;
+	if (mru >= PPP_MRU && mru <= PPP_MAXMRU) {
+	    sc->sc_mru = mru;
+	    if (pppgetm(sc) == 0) {
+		error = ENOBUFS;
+		sc->sc_mru = PPP_MRU;
+		if (pppgetm(sc) == 0)
+		    sc->sc_if.if_flags &= ~IFF_UP;
+	    }
+	}
+	break;
+
+    case PPPIOCGMRU:
+	*(int *)data = sc->sc_mru;
+	break;
+
+#ifdef VJC
+    case PPPIOCSMAXCID:
+	if (error = suser(p->p_ucred, &p->p_acflag))
+	    return (error);
+	sl_compress_setup(&sc->sc_comp, *(int *)data);
+	break;
+#endif
+
+    case PPPIOCXFERUNIT:
+	if (error = suser(p->p_ucred, &p->p_acflag))
+	    return (error);
+	sc->sc_xfer = p->p_pid;
+	break;
+
+    default:
+	return (-1);
+    }
+    return (0);
+}
+
+/*
+ * FCS lookup table as calculated by genfcstab.
+ */
+static u_short fcstab[256] = {
+	0x0000,	0x1189,	0x2312,	0x329b,	0x4624,	0x57ad,	0x6536,	0x74bf,
+	0x8c48,	0x9dc1,	0xaf5a,	0xbed3,	0xca6c,	0xdbe5,	0xe97e,	0xf8f7,
+	0x1081,	0x0108,	0x3393,	0x221a,	0x56a5,	0x472c,	0x75b7,	0x643e,
+	0x9cc9,	0x8d40,	0xbfdb,	0xae52,	0xdaed,	0xcb64,	0xf9ff,	0xe876,
+	0x2102,	0x308b,	0x0210,	0x1399,	0x6726,	0x76af,	0x4434,	0x55bd,
+	0xad4a,	0xbcc3,	0x8e58,	0x9fd1,	0xeb6e,	0xfae7,	0xc87c,	0xd9f5,
+	0x3183,	0x200a,	0x1291,	0x0318,	0x77a7,	0x662e,	0x54b5,	0x453c,
+	0xbdcb,	0xac42,	0x9ed9,	0x8f50,	0xfbef,	0xea66,	0xd8fd,	0xc974,
+	0x4204,	0x538d,	0x6116,	0x709f,	0x0420,	0x15a9,	0x2732,	0x36bb,
+	0xce4c,	0xdfc5,	0xed5e,	0xfcd7,	0x8868,	0x99e1,	0xab7a,	0xbaf3,
+	0x5285,	0x430c,	0x7197,	0x601e,	0x14a1,	0x0528,	0x37b3,	0x263a,
+	0xdecd,	0xcf44,	0xfddf,	0xec56,	0x98e9,	0x8960,	0xbbfb,	0xaa72,
+	0x6306,	0x728f,	0x4014,	0x519d,	0x2522,	0x34ab,	0x0630,	0x17b9,
+	0xef4e,	0xfec7,	0xcc5c,	0xddd5,	0xa96a,	0xb8e3,	0x8a78,	0x9bf1,
+	0x7387,	0x620e,	0x5095,	0x411c,	0x35a3,	0x242a,	0x16b1,	0x0738,
+	0xffcf,	0xee46,	0xdcdd,	0xcd54,	0xb9eb,	0xa862,	0x9af9,	0x8b70,
+	0x8408,	0x9581,	0xa71a,	0xb693,	0xc22c,	0xd3a5,	0xe13e,	0xf0b7,
+	0x0840,	0x19c9,	0x2b52,	0x3adb,	0x4e64,	0x5fed,	0x6d76,	0x7cff,
+	0x9489,	0x8500,	0xb79b,	0xa612,	0xd2ad,	0xc324,	0xf1bf,	0xe036,
+	0x18c1,	0x0948,	0x3bd3,	0x2a5a,	0x5ee5,	0x4f6c,	0x7df7,	0x6c7e,
+	0xa50a,	0xb483,	0x8618,	0x9791,	0xe32e,	0xf2a7,	0xc03c,	0xd1b5,
+	0x2942,	0x38cb,	0x0a50,	0x1bd9,	0x6f66,	0x7eef,	0x4c74,	0x5dfd,
+	0xb58b,	0xa402,	0x9699,	0x8710,	0xf3af,	0xe226,	0xd0bd,	0xc134,
+	0x39c3,	0x284a,	0x1ad1,	0x0b58,	0x7fe7,	0x6e6e,	0x5cf5,	0x4d7c,
+	0xc60c,	0xd785,	0xe51e,	0xf497,	0x8028,	0x91a1,	0xa33a,	0xb2b3,
+	0x4a44,	0x5bcd,	0x6956,	0x78df,	0x0c60,	0x1de9,	0x2f72,	0x3efb,
+	0xd68d,	0xc704,	0xf59f,	0xe416,	0x90a9,	0x8120,	0xb3bb,	0xa232,
+	0x5ac5,	0x4b4c,	0x79d7,	0x685e,	0x1ce1,	0x0d68,	0x3ff3,	0x2e7a,
+	0xe70e,	0xf687,	0xc41c,	0xd595,	0xa12a,	0xb0a3,	0x8238,	0x93b1,
+	0x6b46,	0x7acf,	0x4854,	0x59dd,	0x2d62,	0x3ceb,	0x0e70,	0x1ff9,
+	0xf78f,	0xe606,	0xd49d,	0xc514,	0xb1ab,	0xa022,	0x92b9,	0x8330,
+	0x7bc7,	0x6a4e,	0x58d5,	0x495c,	0x3de3,	0x2c6a,	0x1ef1,	0x0f78
+};
+
+/*
+ * Calculate a new FCS given the current FCS and the new data.
+ */
+static u_short
+pppfcs(fcs, cp, len)
+    register u_short fcs;
+    register u_char *cp;
+    register int len;
+{
+    while (len--)
+	fcs = PPP_FCS(fcs, *cp++);
+    return (fcs);
+}
+
+/*
+ * Queue a packet.  Start transmission if not active.
+ * Packet is placed in Information field of PPP frame.
+ */
+int
+pppoutput(ifp, m0, dst)
+    struct ifnet *ifp;
+    struct mbuf *m0;
+    struct sockaddr *dst;
+{
+    register struct ppp_softc *sc = &ppp_softc[ifp->if_unit];
+    struct ppp_header *ph;
+    int protocol, address, control;
+    u_char *cp;
+    int s, error;
+    struct ip *ip;
+    struct ifqueue *ifq;
+
+    if (sc->sc_devp == NULL || (ifp->if_flags & IFF_RUNNING) == 0
+	|| (ifp->if_flags & IFF_UP) == 0 && dst->sa_family != AF_UNSPEC) {
+	error = ENETDOWN;	/* sort of */
+	goto bad;
+    }
+
+    /*
+     * Compute PPP header.
+     */
+    address = PPP_ALLSTATIONS;
+    control = PPP_UI;
+    ifq = &ifp->if_snd;
+    switch (dst->sa_family) {
+#ifdef INET
+    case AF_INET:
+	protocol = PPP_IP;
+	if ((sc->sc_flags & SC_ENABLE_IP) == 0) {
+	    error = ENETDOWN;
+	    goto bad;
+	}
+	
+	/*
+	 * If this is a TCP packet to or from an "interactive" port,
+	 * put the packet on the fastq instead.
+	 */
+	if ((ip = mtod(m0, struct ip *))->ip_p == IPPROTO_TCP) {
+	    register int p = ntohl(((int *)ip)[ip->ip_hl]);
+	    if (INTERACTIVE(p & 0xffff) || INTERACTIVE(p >> 16))
+		ifq = &sc->sc_fastq;
+	}
+	break;
+#endif
+#ifdef NS
+    case AF_NS:
+	protocol = PPP_XNS;
+	break;
+#endif
+    case AF_UNSPEC:
+	ph = (struct ppp_header *) dst->sa_data;
+	address = ph->ph_address;
+	control = ph->ph_control;
+	protocol = ntohs(ph->ph_protocol);
+	break;
+    default:
+	printf("ppp%d: af%d not supported\n", ifp->if_unit, dst->sa_family);
+	error = EAFNOSUPPORT;
+	goto bad;
+    }
+
+    /*
+     * Add PPP header.  If no space in first mbuf, allocate another.
+     * (This assumes M_LEADINGSPACE is always 0 for a cluster mbuf.)
+     */
+    if (M_LEADINGSPACE(m0) < PPP_HDRLEN) {
+	m0 = m_prepend(m0, PPP_HDRLEN, M_DONTWAIT);
+	if (m0 == 0) {
+	    error = ENOBUFS;
+	    goto bad;
+	}
+	m0->m_len = 0;
+    } else
+	m0->m_data -= PPP_HDRLEN;
+
+    cp = mtod(m0, u_char *);
+    *cp++ = address;
+    *cp++ = control;
+    *cp++ = protocol >> 8;
+    *cp++ = protocol & 0xff;
+    m0->m_len += PPP_HDRLEN;
+
+    if (sc->sc_flags & SC_LOG_OUTPKT) {
+	printf("ppp%d output: ", ifp->if_unit);
+	pppdumpm(m0, -1);
+    }
+
+#if NBPFILTER > 0
+    /* See if bpf wants to look at the packet. */
+    if (sc->sc_bpf)
+	bpf_mtap(sc->sc_bpf, m0);
+#endif
+
+    /*
+     * Put the packet on the appropriate queue.
+     */
+    s = splimp();
+    if (IF_QFULL(ifq)) {
+	IF_DROP(ifq);
+	splx(s);
+	sc->sc_if.if_oerrors++;
+	error = ENOBUFS;
+	goto bad;
+    }
+    IF_ENQUEUE(ifq, m0);
+
+    /*
+     * Tell the device to send it out.
+     */
+    (*sc->sc_start)(sc);
+
+    splx(s);
+    return (0);
+
+bad:
+    m_freem(m0);
+    return (error);
+}
+
+/*
+ * Grab another packet off a queue and apply VJ compression,
+ * address/control and/or protocol compression if appropriate.
+ */
+struct mbuf *
+ppp_dequeue(sc)
+    struct ppp_softc *sc;
+{
+    int s;
+    struct mbuf *m;
+    u_char *cp;
+    int address, control, protocol;
+
+    s = splimp();
+    IF_DEQUEUE(&sc->sc_fastq, m);
+    if (m == NULL)
+	IF_DEQUEUE(&sc->sc_if.if_snd, m);
+    splx(s);
+    if (m == NULL)
+	return NULL;
+
+    /*
+     * Extract the ppp header of the new packet.
+     * The ppp header will be in one mbuf.
+     */
+    cp = mtod(m, u_char *);
+    address = cp[0];
+    control = cp[1];
+    protocol = (cp[2] << 8) + cp[3];
+
+#ifdef VJC
+    /*
+     * If the packet is a TCP/IP packet, see if we can compress it.
+     */
+    if (protocol == PPP_IP && sc->sc_flags & SC_COMP_TCP) {
+	struct ip *ip;
+	int type;
+	struct mbuf *mp;
+
+	mp = m;
+	ip = (struct ip *) (cp + PPP_HDRLEN);
+	if (mp->m_len <= PPP_HDRLEN) {
+	    mp = mp->m_next;
+	    ip = mtod(mp, struct ip *);
+	}
+	/* this code assumes the IP/TCP header is in one non-shared mbuf */
+	if (ip->ip_p == IPPROTO_TCP) {
+	    type = sl_compress_tcp(mp, ip, &sc->sc_comp,
+				   !(sc->sc_flags & SC_NO_TCP_CCID));
+	    switch (type) {
+	    case TYPE_UNCOMPRESSED_TCP:
+		protocol = PPP_VJC_UNCOMP;
+		break;
+	    case TYPE_COMPRESSED_TCP:
+		protocol = PPP_VJC_COMP;
+		cp = mtod(m, u_char *);
+		cp[0] = address;	/* header has moved */
+		cp[1] = control;
+		cp[2] = 0;
+		break;
+	    }
+	    cp[3] = protocol;	/* update protocol in PPP header */
+	}
+    }
+#endif	/* VJC */
+
+#ifdef BSD_COMP
+    if (protocol < PPP_COMP && (sc->sc_flags & SC_BSD_COMP)) {
+	slen = m_totallen(m0);
+	clen = pf_bsd_comp(sc->sc_bsd_db, cbuf, proto, m0, slen);
+    }
+#endif	/* BSD_COMP */
+
+    /*
+     * Compress the address/control and protocol, if possible.
+     */
+    if (sc->sc_flags & SC_COMP_AC && address == PPP_ALLSTATIONS &&
+	control == PPP_UI && protocol != PPP_ALLSTATIONS &&
+	protocol != PPP_LCP) {
+	/* can compress address/control */
+	m->m_data += 2;
+	m->m_len -= 2;
+    }
+    if (sc->sc_flags & SC_COMP_PROT && protocol < 0xFF) {
+	/* can compress protocol */
+	if (mtod(m, u_char *) == cp) {
+	    cp[2] = cp[1];	/* move address/control up */
+	    cp[1] = cp[0];
+	}
+	++m->m_data;
+	--m->m_len;
+    }
+
+    return m;
+}
+
+/*
+ * This gets called from pppoutput when a new packet is
+ * put on a queue.
+ */
+static
+pppasyncstart(sc)
+    register struct ppp_softc *sc;
+{
+    register struct tty *tp = (struct tty *) sc->sc_devp;
+
+    pppstart(tp);
+}
+
+/*
+ * Start output on async tty interface.  Get another datagram
+ * to send from the interface queue and start sending it.
+ */
+void
+pppstart(tp)
+    register struct tty *tp;
+{
+    register struct ppp_softc *sc = (struct ppp_softc *) tp->t_sc;
+    register struct mbuf *m;
+    register int len;
+    register u_char *start, *stop, *cp;
+    int n, s, ndone, done;
+    struct mbuf *m2;
+
+    if ((tp->t_state & TS_CARR_ON) == 0 && (tp->t_cflag & CLOCAL) == 0) {
+	/* sorry, I can't talk now */
+	return;
+    }
+    if (sc == NULL || tp != (struct tty *) sc->sc_devp) {
+	(*tp->t_oproc)(tp);
+	return;
+    }
+
+    for (;;) {
+	/*
+	 * If there is more in the output queue, just send it now.
+	 * We are being called in lieu of ttstart and must do what
+	 * it would.
+	 */
+	if (CCOUNT(&tp->t_outq) != 0 && tp->t_oproc != NULL) {
+	    (*tp->t_oproc)(tp);
+	    if (CCOUNT(&tp->t_outq) > PPP_HIWAT)
+		return;
+	}
+
+	/*
+	 * See if we have an existing packet partly sent.
+	 * If not, get a new packet and start sending it.
+	 * We take packets on the priority queue ahead of those
+	 * on the normal queue.
+	 */
+	m = sc->sc_outm;
+	if (m == NULL) {
+	    /*
+	     * Get another packet to be sent
+	     */
+	    m = ppp_dequeue(sc);
+	    if (m == NULL)
+		return;
+
+	    /*
+	     * The extra PPP_FLAG will start up a new packet, and thus
+	     * will flush any accumulated garbage.  We do this whenever
+	     * the line may have been idle for some time.
+	     */
+	    if (CCOUNT(&tp->t_outq) == 0) {
+		++sc->sc_bytessent;
+		(void) putc(PPP_FLAG, &tp->t_outq);
+	    }
+
+	    /* Calculate the FCS for the first mbuf's worth. */
+	    sc->sc_outfcs = pppfcs(PPP_INITFCS, mtod(m, u_char *), m->m_len);
+	}
+
+	for (;;) {
+	    start = mtod(m, u_char *);
+	    len = m->m_len;
+	    stop = start + len;
+	    while (len > 0) {
+		/*
+		 * Find out how many bytes in the string we can
+		 * handle without doing something special.
+		 */
+		for (cp = start; cp < stop; cp++)
+		    if (ESCAPE_P(*cp))
+			break;
+		n = cp - start;
+		if (n) {
+		    /* NetBSD (0.9 or later), 4.3-Reno or similar. */
+		    ndone = n - b_to_q(start, n, &tp->t_outq);
+		    len -= ndone;
+		    start += ndone;
+		    sc->sc_bytessent += ndone;
+
+		    if (ndone < n)
+			break;	/* packet doesn't fit */
+		}
+		/*
+		 * If there are characters left in the mbuf,
+		 * the first one must be special..
+		 * Put it out in a different form.
+		 */
+		if (len) {
+		    if (putc(PPP_ESCAPE, &tp->t_outq))
+			break;
+		    if (putc(*start ^ PPP_TRANS, &tp->t_outq)) {
+			(void) unputc(&tp->t_outq);
+			break;
+		    }
+		    sc->sc_bytessent += 2;
+		    start++;
+		    len--;
+		}
+	    }
+	    /*
+	     * If we didn't empty this mbuf, remember where we're up to.
+	     * If we emptied the last mbuf, try to add the FCS and closing
+	     * flag, and if we can't, leave sc_outm pointing to m, but with
+	     * m->m_len == 0, to remind us to output the FCS and flag later.
+	     */
+	    done = len == 0;
+	    if (done && m->m_next == NULL) {
+		u_char *p, *q;
+		int c;
+		u_char endseq[8];
+
+		/*
+		 * We may have to escape the bytes in the FCS.
+		 */
+		p = endseq;
+		c = ~sc->sc_outfcs & 0xFF;
+		if (ESCAPE_P(c)) {
+		    *p++ = PPP_ESCAPE;
+		    *p++ = c ^ PPP_TRANS;
+		} else
+		    *p++ = c;
+		c = (~sc->sc_outfcs >> 8) & 0xFF;
+		if (ESCAPE_P(c)) {
+		    *p++ = PPP_ESCAPE;
+		    *p++ = c ^ PPP_TRANS;
+		} else
+		    *p++ = c;
+		*p++ = PPP_FLAG;
+
+		/*
+		 * Try to output the FCS and flag.  If the bytes
+		 * don't all fit, back out.
+		 */
+		for (q = endseq; q < p; ++q)
+		    if (putc(*q, &tp->t_outq)) {
+			done = 0;
+			for (; q > endseq; --q)
+			    unputc(&tp->t_outq);
+			break;
+		    }
+	    }
+
+	    if (!done) {
+		m->m_data = start;
+		m->m_len = len;
+		sc->sc_outm = m;
+		if (tp->t_oproc != NULL)
+		    (*tp->t_oproc)(tp);
+		return;		/* can't do any more at the moment */
+	    }
+
+	    /* Finished with this mbuf; free it and move on. */
+	    MFREE(m, m2);
+	    if (m2 == NULL)
+		break;
+
+	    m = m2;
+	    sc->sc_outfcs = pppfcs(sc->sc_outfcs, mtod(m, u_char *), m->m_len);
+	}
+
+	/* Finished a packet */
+	sc->sc_outm = NULL;
+	sc->sc_bytessent++;	/* account for closing flag */
+	sc->sc_if.if_opackets++;
+	sc->sc_if.if_obytes = sc->sc_bytessent;
+    }
+}
+
+/*
+ * Allocate enough mbuf to handle current MRU.
+ */
+static int
+pppgetm(sc)
+    register struct ppp_softc *sc;
+{
+    struct mbuf *m, **mp;
+    int len = HDROFF + sc->sc_mru + PPP_HDRLEN + PPP_FCSLEN;
+    int s;
+
+    s = splimp();
+    for (mp = &sc->sc_m; (m = *mp) != NULL; mp = &m->m_next)
+	if ((len -= M_DATASIZE(m)) <= 0) {
+	    splx(s);
+	    return (1);
+	}
+
+    for (;; mp = &m->m_next) {
+	MGETHDR(m, M_DONTWAIT, MT_DATA);
+	if (m == 0) {
+	    m_freem(sc->sc_m);
+	    sc->sc_m = NULL;
+	    splx(s);
+	    printf("ppp%d: can't allocate mbuf\n", sc->sc_if.if_unit);
+	    return (0);
+	}
+	*mp = m;
+	MCLGET(m, M_DONTWAIT);
+	if ((len -= M_DATASIZE(m)) <= 0) {
+	    splx(s);
+	    return (1);
+	}
+    }
+}
+
+/*
+ * Copy mbuf chain.  Would like to use m_copy(), but we need a real copy
+ * of the data, not just copies of pointers to the data.
+ */
+static struct mbuf *
+ppp_btom(sc)
+    struct ppp_softc *sc;
+{
+    register struct mbuf *m, **mp;
+    struct mbuf *top = sc->sc_m;
+
+    /*
+     * First check current mbuf.  If we have more than a small mbuf,
+     * return the whole cluster and set beginning of buffer to the
+     * next mbuf.
+     * Else, copy the current bytes into a small mbuf, attach the new
+     * mbuf to the end of the chain and set beginning of buffer to the
+     * current mbuf.
+     */
+
+    if (sc->sc_mc->m_len > MHLEN) {
+	sc->sc_m = sc->sc_mc->m_next;
+	sc->sc_mc->m_next = NULL;
+    }
+    else {
+	/* rather than waste a whole cluster on <= MHLEN bytes,
+	   alloc a small mbuf and copy to it */
+	MGETHDR(m, M_DONTWAIT, MT_DATA);
+	if (m == NULL)
+	    return (NULL);
+
+	bcopy(mtod(sc->sc_mc, caddr_t), mtod(m, caddr_t), sc->sc_mc->m_len);
+	m->m_len = sc->sc_mc->m_len;
+	for (mp = &top; *mp != sc->sc_mc; mp = &(*mp)->m_next)
+	    ;
+	*mp = m;
+	sc->sc_m = sc->sc_mc;
+    }
+
+    /*
+     * Try to allocate enough extra mbufs to handle the next packet.
+     */
+    if (pppgetm(sc) == 0) {
+	m_freem(top);
+	if (pppgetm(sc) == 0)
+	    sc->sc_if.if_flags &= ~IFF_UP;
+	return (NULL);
+    }
+
+    return (top);
+}
+
+/*
+ * PPP packet input routine.
+ * The caller has checked and removed the FCS.
+ * The return value is 1 if the packet was put on sc->sc_inq,
+ * 0 otherwise.
+ */
+#define COMPTYPE(proto)	((proto) == PPP_VJC_COMP? TYPE_COMPRESSED_TCP: \
+			 TYPE_UNCOMPRESSED_TCP)
+
+int
+ppppktin(sc, m, ilen)
+    struct ppp_softc *sc;
+    struct mbuf *m;
+    int ilen;
+{
+    struct ifqueue *inq;
+    int s, xlen, proto, rv;
+    struct ppp_header hdr;
+
+    sc->sc_if.if_ipackets++;
+    rv = 0;
+
+    hdr = *mtod(m, struct ppp_header *);
+    proto = ntohs(hdr.ph_protocol);
+
+#ifdef VJC
+    /*
+     * See if we have a VJ-compressed packet to uncompress.
+     */
+    if (proto == PPP_VJC_COMP || proto == PPP_VJC_UNCOMP) {
+	char *pkttype = proto == PPP_VJC_COMP? "": "un";
+
+	if (sc->sc_flags & SC_REJ_COMP_TCP) {
+	    if (sc->sc_flags & SC_DEBUG)
+		printf("ppp%d: %scomp pkt w/o compression; flags 0x%x\n",
+			sc->sc_if.if_unit, pkttype, sc->sc_flags);
+	    sc->sc_if.if_ierrors++;
+	    return 0;
+	}
+
+	m->m_data += PPP_HDRLEN;
+	m->m_len -= PPP_HDRLEN;
+	ilen -= PPP_HDRLEN;
+	xlen = sl_uncompress_tcp_part((u_char **)(&m->m_data),
+					m->m_len, ilen,
+					COMPTYPE(proto), &sc->sc_comp);
+
+	if (xlen == 0) {
+	    if (sc->sc_flags & SC_DEBUG)
+		printf("ppp%d: sl_uncompress failed on type %scomp\n",
+			sc->sc_if.if_unit, pkttype);
+	    sc->sc_if.if_ierrors++;
+	    return 0;
+	}
+
+	/* adjust the first mbuf by the decompressed amt */
+	xlen += PPP_HDRLEN;
+	m->m_len += xlen - ilen;
+	ilen = xlen;
+	m->m_data -= PPP_HDRLEN;
+	proto = PPP_IP;
+
+	/* put the ppp header back in place */
+	hdr.ph_protocol = htons(PPP_IP);
+	*mtod(m, struct ppp_header *) = hdr;
+    }
+#endif /* VJC */
+
+    /* get this packet as an mbuf chain */
+    if ((m = ppp_btom(sc)) == NULL) {
+	sc->sc_if.if_ierrors++;
+	return 0;
+    }
+    m->m_pkthdr.len = ilen;
+    m->m_pkthdr.rcvif = &sc->sc_if;
+
+#if NBPFILTER > 0
+    /* See if bpf wants to look at the packet. */
+    if (sc->sc_bpf)
+	bpf_mtap(sc->sc_bpf, m);
+#endif
+
+    switch (proto) {
+#ifdef INET
+    case PPP_IP:
+	/*
+	 * IP packet - take off the ppp header and pass it up to IP.
+	 */
+	if ((sc->sc_if.if_flags & IFF_UP) == 0
+	    || (sc->sc_flags & SC_ENABLE_IP) == 0) {
+	    /* interface is down - drop the packet. */
+	    m_freem(m);
+	    return 0;
+	}
+	m->m_pkthdr.len -= PPP_HDRLEN;
+	m->m_data += PPP_HDRLEN;
+	m->m_len -= PPP_HDRLEN;
+	schednetisr(NETISR_IP);
+	inq = &ipintrq;
+	break;
+#endif
+
+    default:
+	/*
+	 * Some other protocol - place on input queue for read().
+	 */
+	inq = &sc->sc_inq;
+	rv = 1;
+	break;
+    }
+
+    /*
+     * Put the packet on the appropriate input queue.
+     */
+    s = splimp();
+    if (IF_QFULL(inq)) {
+	IF_DROP(inq);
+	if (sc->sc_flags & SC_DEBUG)
+	    printf("ppp%d: queue full\n", sc->sc_if.if_unit);
+	sc->sc_if.if_ierrors++;
+	sc->sc_if.if_iqdrops++;
+	m_freem(m);
+	rv = 0;
+    } else
+	IF_ENQUEUE(inq, m);
+
+    splx(s);
+    return rv;
+}
+
+/*
+ * tty interface receiver interrupt.
+ */
+static unsigned paritytab[8] = {
+    0x96696996, 0x69969669, 0x69969669, 0x96696996,
+    0x69969669, 0x96696996, 0x96696996, 0x69969669
+};
+
+void
+pppinput(c, tp)
+    int c;
+    register struct tty *tp;
+{
+    register struct ppp_softc *sc;
+    struct mbuf *m;
+    int ilen;
+
+    tk_nin++;
+    sc = (struct ppp_softc *) tp->t_sc;
+    if (sc == NULL || tp != (struct tty *) sc->sc_devp)
+	return;
+
+    ++sc->sc_bytesrcvd;
+
+    if (c & TTY_FE) {
+	/* framing error or overrun on this char - abort packet */
+	if (sc->sc_flags & SC_DEBUG)
+	    printf("ppp%d: bad char %x\n", sc->sc_if.if_unit, c);
+	goto flush;
+    }
+
+    c &= 0xff;
+
+    if (c & 0x80)
+	sc->sc_flags |= SC_RCV_B7_1;
+    else
+	sc->sc_flags |= SC_RCV_B7_0;
+    if (paritytab[c >> 5] & (1 << (c & 0x1F)))
+	sc->sc_flags |= SC_RCV_ODDP;
+    else
+	sc->sc_flags |= SC_RCV_EVNP;
+
+    if (sc->sc_flags & SC_LOG_RAWIN)
+	ppplogchar(sc, c);
+
+    if (c == PPP_FLAG) {
+	ilen = sc->sc_ilen;
+	sc->sc_ilen = 0;
+	sc->sc_if.if_ibytes = sc->sc_bytesrcvd;
+
+	if (sc->sc_rawin_count > 0) 
+	    ppplogchar(sc, -1);
+
+	/*
+	 * If SC_ESCAPED is set, then we've seen the packet
+	 * abort sequence "}~".
+	 */
+	if (sc->sc_flags & (SC_FLUSH | SC_ESCAPED)
+	    || ilen > 0 && sc->sc_fcs != PPP_GOODFCS) {
+#ifdef VJC
+	    /*
+	     * If we've missed a packet, we must toss subsequent compressed
+	     * packets which don't have an explicit connection ID.
+	     */
+	    sl_uncompress_tcp(NULL, 0, TYPE_ERROR, &sc->sc_comp);
+#endif
+	    if ((sc->sc_flags & (SC_FLUSH | SC_ESCAPED)) == 0){
+		if (sc->sc_flags & SC_DEBUG)
+		    printf("ppp%d: bad fcs\n", sc->sc_if.if_unit);
+		sc->sc_if.if_ierrors++;
+	    } else
+		sc->sc_flags &= ~(SC_FLUSH | SC_ESCAPED);
+	    return;
+	}
+
+	if (ilen < PPP_HDRLEN + PPP_FCSLEN) {
+	    if (ilen) {
+		if (sc->sc_flags & SC_DEBUG)
+		    printf("ppp%d: too short (%d)\n", sc->sc_if.if_unit, ilen);
+		sc->sc_if.if_ierrors++;
+	    }
+	    return;
+	}
+
+	/*
+	 * Remove FCS trailer.  Somewhat painful...
+	 */
+	ilen -= 2;
+	if (--sc->sc_mc->m_len == 0) {
+	    for (m = sc->sc_m; m->m_next != sc->sc_mc; m = m->m_next)
+		;
+	    sc->sc_mc = m;
+	}
+	sc->sc_mc->m_len--;
+
+	m = sc->sc_m;
+
+	if (sc->sc_flags & SC_LOG_INPKT) {
+	    printf("ppp%d: got %d bytes\n", sc->sc_if.if_unit, ilen);
+	    pppdumpm(m, ilen);
+	}
+
+	if (ppppktin(sc, m, ilen)) {
+	    /* Put a placeholder byte in canq for ttselect()/ttnread(). */
+	    putc(0, &tp->t_canq);
+	    ttwakeup(tp);
+	}
+	return;
+    }
+
+    if (sc->sc_flags & SC_FLUSH) {
+	if (sc->sc_flags & SC_LOG_FLUSH)
+	    ppplogchar(sc, c);
+	return;
+    }
+
+    if (c < 0x20 && (sc->sc_rasyncmap & (1 << c)))
+	return;
+
+    if (sc->sc_flags & SC_ESCAPED) {
+	sc->sc_flags &= ~SC_ESCAPED;
+	c ^= PPP_TRANS;
+    } else if (c == PPP_ESCAPE) {
+	sc->sc_flags |= SC_ESCAPED;
+	return;
+    }
+
+    /*
+     * Initialize buffer on first octet received.
+     * First octet could be address or protocol (when compressing
+     * address/control).
+     * Second octet is control.
+     * Third octet is first or second (when compressing protocol)
+     * octet of protocol.
+     * Fourth octet is second octet of protocol.
+     */
+    if (sc->sc_ilen == 0) {
+	/* reset the first input mbuf */
+	m = sc->sc_m;
+	m->m_len = 0;
+	m->m_data = M_DATASTART(sc->sc_m) + HDROFF;
+	sc->sc_mc = m;
+	sc->sc_mp = mtod(m, char *);
+	sc->sc_fcs = PPP_INITFCS;
+	if (c != PPP_ALLSTATIONS) {
+	    if (sc->sc_flags & SC_REJ_COMP_AC) {
+		if (sc->sc_flags & SC_DEBUG)
+		    printf("ppp%d: garbage received: 0x%x (need 0xFF)\n",
+			   sc->sc_if.if_unit, c);
+		goto flush;
+	    }
+	    *sc->sc_mp++ = PPP_ALLSTATIONS;
+	    *sc->sc_mp++ = PPP_UI;
+	    sc->sc_ilen += 2;
+	    m->m_len += 2;
+	}
+    }
+    if (sc->sc_ilen == 1 && c != PPP_UI) {
+	if (sc->sc_flags & SC_DEBUG)
+	    printf("ppp%d: missing UI (0x3), got 0x%x\n",
+		   sc->sc_if.if_unit, c);
+	goto flush;
+    }
+    if (sc->sc_ilen == 2 && (c & 1) == 1) {
+	/* a compressed protocol */
+	*sc->sc_mp++ = 0;
+	sc->sc_ilen++;
+	sc->sc_mc->m_len++;
+    }
+    if (sc->sc_ilen == 3 && (c & 1) == 0) {
+	if (sc->sc_flags & SC_DEBUG)
+	    printf("ppp%d: bad protocol %x\n", sc->sc_if.if_unit,
+		   (sc->sc_mp[-1] << 8) + c);
+	goto flush;
+    }
+
+    /* packet beyond configured mru? */
+    if (++sc->sc_ilen > sc->sc_mru + PPP_HDRLEN + PPP_FCSLEN) {
+	if (sc->sc_flags & SC_DEBUG)
+	    printf("ppp%d: packet too big\n", sc->sc_if.if_unit);
+	goto flush;
+    }
+
+    /* is this mbuf full? */
+    m = sc->sc_mc;
+    if (M_TRAILINGSPACE(m) <= 0) {
+	sc->sc_mc = m = m->m_next;
+	if (m == NULL) {
+	    printf("ppp%d: too few input mbufs!\n", sc->sc_if.if_unit);
+	    goto flush;
+	}
+	m->m_len = 0;
+	m->m_data = M_DATASTART(m);
+	sc->sc_mp = mtod(m, char *);
+    }
+
+    ++m->m_len;
+    *sc->sc_mp++ = c;
+    sc->sc_fcs = PPP_FCS(sc->sc_fcs, c);
+    return;
+
+ flush:
+    if (!(sc->sc_flags & SC_FLUSH)) {
+	sc->sc_if.if_ierrors++;
+	sc->sc_flags |= SC_FLUSH;
+	if (sc->sc_flags & SC_LOG_FLUSH)
+	    ppplogchar(sc, c);
+    }
+}
+
+/*
+ * Process an ioctl request to interface.
+ */
+pppioctl(ifp, cmd, data)
+    register struct ifnet *ifp;
+    int cmd;
+    caddr_t data;
+{
+    struct proc *p = curproc;	/* XXX */
+    register struct ppp_softc *sc = &ppp_softc[ifp->if_unit];
+    register struct ifaddr *ifa = (struct ifaddr *)data;
+    register struct ifreq *ifr = (struct ifreq *)data;
+    int s = splimp(), error = 0;
+
+
+    switch (cmd) {
+    case SIOCSIFFLAGS:
+	if ((ifp->if_flags & IFF_RUNNING) == 0)
+	    ifp->if_flags &= ~IFF_UP;
+	break;
+
+    case SIOCSIFADDR:
+	if (ifa->ifa_addr->sa_family != AF_INET)
+	    error = EAFNOSUPPORT;
+	break;
+
+    case SIOCSIFDSTADDR:
+	if (ifa->ifa_addr->sa_family != AF_INET)
+	    error = EAFNOSUPPORT;
+	break;
+
+    case SIOCSIFMTU:
+	if (error = suser(p->p_ucred, &p->p_acflag))
+	    return (error);
+	sc->sc_if.if_mtu = ifr->ifr_mtu;
+	break;
+
+    case SIOCGIFMTU:
+	ifr->ifr_mtu = sc->sc_if.if_mtu;
+	break;
+
+    default:
+	error = EINVAL;
+    }
+    splx(s);
+    return (error);
+}
+
+#define MAX_DUMP_BYTES	128
+
+static void
+pppdumpm(m0, pktlen)
+    struct mbuf *m0;
+    int pktlen;
+{
+    char buf[3*MAX_DUMP_BYTES+4];
+    char *bp = buf;
+    struct mbuf *m;
+    static char digits[] = "0123456789abcdef";
+
+    for (m = m0; m && pktlen; m = m->m_next) {
+	int l = m->m_len;
+	u_char *rptr = (u_char *)m->m_data;
+
+	if (pktlen > 0) {
+	    if (l > pktlen)
+		l = pktlen;
+	    pktlen -= l;
+	}
+	while (l--) {
+	    if (bp > buf + sizeof(buf) - 4)
+		goto done;
+	    *bp++ = digits[*rptr >> 4]; /* convert byte to ascii hex */
+	    *bp++ = digits[*rptr++ & 0xf];
+	}
+
+	if (m->m_next) {
+	    if (bp > buf + sizeof(buf) - 3)
+		goto done;
+	    *bp++ = '|';
+	} else
+	    *bp++ = ' ';
+    }
+done:
+    if (m && pktlen)
+	*bp++ = '>';
+    *bp = 0;
+    printf("%s\n", buf);
+}
+
+static void
+ppplogchar(sc, c)
+    struct ppp_softc *sc;
+    int c;
+{
+    if (c >= 0)
+	sc->sc_rawin[sc->sc_rawin_count++] = c;
+    if (sc->sc_rawin_count >= sizeof(sc->sc_rawin)
+	|| c < 0 && sc->sc_rawin_count > 0) {
+	printf("ppp%d input: ", sc->sc_if.if_unit);
+	pppdumpb(sc->sc_rawin, sc->sc_rawin_count);
+	sc->sc_rawin_count = 0;
+    }
+}
+
+static void
+pppdumpb(b, l)
+    u_char *b;
+    int l;
+{
+    char buf[3*MAX_DUMP_BYTES+4];
+    char *bp = buf;
+    static char digits[] = "0123456789abcdef";
+
+    while (l--) {
+	if (bp >= buf + sizeof(buf) - 3) {
+	    *bp++ = '>';
+	    break;
+	}
+	*bp++ = digits[*b >> 4]; /* convert byte to ascii hex */
+	*bp++ = digits[*b++ & 0xf];
+	*bp++ = ' ';
+    }
+
+    *bp = 0;
+    printf("%s\n", buf);
+}
+
+
+#endif	/* NPPP > 0 */
diff --git a/sys/net/if_ppp.h b/sys/net/if_ppp.h
new file mode 100644
index 0000000..9f70af0
--- /dev/null
+++ b/sys/net/if_ppp.h
@@ -0,0 +1,146 @@
+/*
+ * if_ppp.h - Point-to-Point Protocol definitions.
+ *
+ * Copyright (c) 1989 Carnegie Mellon University.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms are permitted
+ * provided that the above copyright notice and this paragraph are
+ * duplicated in all such forms and that any documentation,
+ * advertising materials, and other materials related to such
+ * distribution and use acknowledge that the software was developed
+ * by Carnegie Mellon University.  The name of the
+ * University may not be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * $Id: if_ppp.h,v 1.5 1994/01/25 05:56:08 deraadt Exp $
+ */
+
+#ifndef _IF_PPP_H_
+#define _IF_PPP_H_
+
+/*
+ * Standard PPP header.
+ */
+struct ppp_header {
+	u_char	ph_address;	/* Address Field */
+	u_char	ph_control;	/* Control Field */
+	u_short	ph_protocol;	/* Protocol Field */
+};
+
+#define PPP_HDRLEN	4	/* sizeof(struct ppp_header) must be 4 */
+#define PPP_FCSLEN	2	/* octets for FCS */
+
+#define	PPP_ALLSTATIONS	0xff	/* All-Stations broadcast address */
+#define	PPP_UI		0x03	/* Unnumbered Information */
+#define	PPP_FLAG	0x7e	/* Flag Sequence */
+#define	PPP_ESCAPE	0x7d	/* Asynchronous Control Escape */
+#define	PPP_TRANS	0x20	/* Asynchronous transparency modifier */
+
+/*
+ * Protocol field values.
+ */
+#define PPP_IP		0x21	/* Internet Protocol */
+#define	PPP_XNS		0x25	/* Xerox NS */
+#define	PPP_VJC_COMP	0x2d	/* VJ compressed TCP */
+#define	PPP_VJC_UNCOMP	0x2f	/* VJ uncompressed TCP */
+#define PPP_COMP	0xfd	/* compressed packet */
+#define PPP_LCP		0xc021	/* Link Control Protocol */
+#define PPP_CCP		0x80fd	/* Compression Control Protocol */
+
+/*
+ * Important FCS values.
+ */
+#define PPP_INITFCS	0xffff	/* Initial FCS value */
+#define PPP_GOODFCS	0xf0b8	/* Good final FCS value */
+#define PPP_FCS(fcs, c)	(((fcs) >> 8) ^ fcstab[((fcs) ^ (c)) & 0xff])
+
+/*
+ * Packet sizes
+ */
+#define	PPP_MTU		1500	/* Default MTU (size of Info field) */
+#define PPP_MRU		1500	/* Default MRU (max receive unit) */
+#define PPP_MAXMRU	65000	/* Largest MRU we allow */
+
+/* Extended asyncmap - allows any character to be escaped. */
+typedef u_long	ext_accm[8];
+
+/*
+ * Structure describing each ppp unit.
+ */
+struct ppp_softc {
+	struct ifnet sc_if;	/* network-visible interface */
+	u_int	sc_flags;	/* see below */
+	void	*sc_devp;	/* pointer to device-dependent structure */
+	int	(*sc_start) __P((struct ppp_softc *));	/* start routine */
+	short	sc_mru;		/* max receive unit */
+	pid_t	sc_xfer;	/* used in xferring unit to another dev */
+	struct	ifqueue sc_inq;	/* TTY side input queue */
+	struct	ifqueue sc_fastq; /* IP interactive output packet queue */
+#ifdef	VJC
+	struct	slcompress sc_comp; /* vjc control buffer */
+#endif
+	u_int	sc_bytessent;	/* count of octets sent */
+	u_int	sc_bytesrcvd;	/* count of octets received */
+	caddr_t	sc_bpf;		/* hook for BPF */
+	
+	/* Device-dependent part for async lines. */
+	ext_accm sc_asyncmap;	/* async control character map */
+	u_long	sc_rasyncmap;	/* receive async control char map */
+	struct	mbuf *sc_outm;	/* mbuf chain being output currently */
+	struct	mbuf *sc_m;	/* pointer to input mbuf chain */
+	struct	mbuf *sc_mc;	/* pointer to current input mbuf */
+	char	*sc_mp;		/* pointer to next char in input mbuf */
+	short	sc_ilen;	/* length of input-packet-so-far */
+	u_short	sc_fcs;		/* FCS so far (input) */
+	u_short	sc_outfcs;	/* FCS so far for output packet */
+	u_char	sc_rawin[16];	/* chars as received */
+	int	sc_rawin_count;	/* # in sc_rawin */
+};
+
+/* flags */
+#define SC_COMP_PROT	0x00000001	/* protocol compression (output) */
+#define SC_COMP_AC	0x00000002	/* header compression (output) */
+#define	SC_COMP_TCP	0x00000004	/* TCP (VJ) compression (output) */
+#define SC_NO_TCP_CCID	0x00000008	/* disable VJ connection-id comp. */
+#define SC_REJ_COMP_AC	0x00000010	/* reject adrs/ctrl comp. on input */
+#define SC_REJ_COMP_TCP	0x00000020	/* reject TCP (VJ) comp. on input */
+#define SC_ENABLE_IP	0x00000100	/* IP packets may be exchanged */
+#define SC_DEBUG	0x00010000	/* enable debug messages */
+#define SC_LOG_INPKT	0x00020000	/* log contents of good pkts recvd */
+#define SC_LOG_OUTPKT	0x00040000	/* log contents of pkts sent */
+#define SC_LOG_RAWIN	0x00080000	/* log all chars received */
+#define SC_LOG_FLUSH	0x00100000	/* log all chars flushed */
+#define	SC_MASK		0x0fffffff	/* bits that user can change */
+
+/* state bits */
+#define	SC_ESCAPED	0x80000000	/* saw a PPP_ESCAPE */
+#define	SC_FLUSH	0x40000000	/* flush input until next PPP_FLAG */
+#define SC_RCV_B7_0	0x01000000	/* have rcvd char with bit 7 = 0 */
+#define SC_RCV_B7_1	0x02000000	/* have rcvd char with bit 7 = 0 */
+#define SC_RCV_EVNP	0x04000000	/* have rcvd char with even parity */
+#define SC_RCV_ODDP	0x08000000	/* have rcvd char with odd parity */
+
+/* this stuff doesn't belong here... */
+#define	PPPIOCGFLAGS	_IOR('t', 90, int)	/* get configuration flags */
+#define	PPPIOCSFLAGS	_IOW('t', 89, int)	/* set configuration flags */
+#define	PPPIOCGASYNCMAP	_IOR('t', 88, int)	/* get async map */
+#define	PPPIOCSASYNCMAP	_IOW('t', 87, int)	/* set async map */
+#define	PPPIOCGUNIT	_IOR('t', 86, int)	/* get ppp unit number */
+#define	PPPIOCGRASYNCMAP _IOR('t', 85, int)	/* get receive async map */
+#define	PPPIOCSRASYNCMAP _IOW('t', 84, int)	/* set receive async map */
+#define	PPPIOCGMRU	_IOR('t', 83, int)	/* get max receive unit */
+#define	PPPIOCSMRU	_IOW('t', 82, int)	/* set max receive unit */
+#define	PPPIOCSMAXCID	_IOW('t', 81, int)	/* set VJ max slot ID */
+#define PPPIOCGXASYNCMAP _IOR('t', 80, ext_accm) /* get extended ACCM */
+#define PPPIOCSXASYNCMAP _IOW('t', 79, ext_accm) /* set extended ACCM */
+#define PPPIOCXFERUNIT	_IO('t', 78)		/* transfer PPP unit */
+
+#if !defined(ifr_mtu)
+#define ifr_mtu	ifr_metric
+#endif
+
+#endif /* _IF_PPP_H_ */
diff --git a/sys/net/pppcompress.c b/sys/net/pppcompress.c
new file mode 100644
index 0000000..d2d5726
--- /dev/null
+++ b/sys/net/pppcompress.c
@@ -0,0 +1,592 @@
+/*-
+ * Copyright (c) 1989 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)slcompress.c	7.7 (Berkeley) 5/7/91
+ */
+
+/*
+ * Routines to compress and uncompess tcp packets (for transmission
+ * over low speed serial lines.
+ *
+ * Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
+ *    - Initial distribution.
+ *
+ * Modified June 1993 by Paul Mackerras, paulus@cs.anu.edu.au,
+ * so that the entire packet being decompressed doesn't have
+ * to be in contiguous memory (just the compressed header).
+ *
+ *	$Id: slcompress.c,v 1.6 1994/01/21 06:33:31 glass Exp $
+ */
+  
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/mbuf.h>
+#include <sys/socketvar.h>
+
+#include <netinet/in.h>
+#include <netinet/in_systm.h>
+#include <netinet/ip.h>
+#include <netinet/tcp.h>
+
+#include <net/slcompress.h>
+
+#ifndef SL_NO_STATS
+#define INCR(counter) ++comp->counter;
+#else
+#define INCR(counter)
+#endif
+
+#define BCMP(p1, p2, n) bcmp((char *)(p1), (char *)(p2), (int)(n))
+#define BCOPY(p1, p2, n) bcopy((char *)(p1), (char *)(p2), (int)(n))
+#ifndef KERNEL
+#define ovbcopy bcopy
+#endif
+
+
+void
+sl_compress_init(comp)
+	struct slcompress *comp;
+{
+	register u_int i;
+	register struct cstate *tstate = comp->tstate;
+
+	bzero((char *)comp, sizeof(*comp));
+	for (i = MAX_STATES - 1; i > 0; --i) {
+		tstate[i].cs_id = i;
+		tstate[i].cs_next = &tstate[i - 1];
+	}
+	tstate[0].cs_next = &tstate[MAX_STATES - 1];
+	tstate[0].cs_id = 0;
+	comp->last_cs = &tstate[0];
+	comp->last_recv = 255;
+	comp->last_xmit = 255;
+	comp->flags = SLF_TOSS;
+}
+
+
+/*
+ * Like sl_compress_init, but we get to specify the maximum connection
+ * ID to use on transmission.
+ */
+void
+sl_compress_setup(comp, max_state)
+	struct slcompress *comp;
+	int max_state;
+{
+	register u_int i;
+	register struct cstate *tstate = comp->tstate;
+
+	if ((unsigned) max_state > MAX_STATES - 1)
+		max_state = MAX_STATES - 1;
+	bzero((char *)comp, sizeof(*comp));
+	for (i = max_state; i > 0; --i) {
+		tstate[i].cs_id = i;
+		tstate[i].cs_next = &tstate[i - 1];
+	}
+	tstate[0].cs_next = &tstate[max_state];
+	tstate[0].cs_id = 0;
+	comp->last_cs = &tstate[0];
+	comp->last_recv = 255;
+	comp->last_xmit = 255;
+	comp->flags = SLF_TOSS;
+}
+
+
+/* ENCODE encodes a number that is known to be non-zero.  ENCODEZ
+ * checks for zero (since zero has to be encoded in the long, 3 byte
+ * form).
+ */
+#define ENCODE(n) { \
+	if ((u_short)(n) >= 256) { \
+		*cp++ = 0; \
+		cp[1] = (n); \
+		cp[0] = (n) >> 8; \
+		cp += 2; \
+	} else { \
+		*cp++ = (n); \
+	} \
+}
+#define ENCODEZ(n) { \
+	if ((u_short)(n) >= 256 || (u_short)(n) == 0) { \
+		*cp++ = 0; \
+		cp[1] = (n); \
+		cp[0] = (n) >> 8; \
+		cp += 2; \
+	} else { \
+		*cp++ = (n); \
+	} \
+}
+
+#define DECODEL(f) { \
+	if (*cp == 0) {\
+		(f) = htonl(ntohl(f) + ((cp[1] << 8) | cp[2])); \
+		cp += 3; \
+	} else { \
+		(f) = htonl(ntohl(f) + (u_long)*cp++); \
+	} \
+}
+
+#define DECODES(f) { \
+	if (*cp == 0) {\
+		(f) = htons(ntohs(f) + ((cp[1] << 8) | cp[2])); \
+		cp += 3; \
+	} else { \
+		(f) = htons(ntohs(f) + (u_long)*cp++); \
+	} \
+}
+
+#define DECODEU(f) { \
+	if (*cp == 0) {\
+		(f) = htons((cp[1] << 8) | cp[2]); \
+		cp += 3; \
+	} else { \
+		(f) = htons((u_long)*cp++); \
+	} \
+}
+
+
+u_char
+sl_compress_tcp(m, ip, comp, compress_cid)
+	struct mbuf *m;
+	register struct ip *ip;
+	struct slcompress *comp;
+	int compress_cid;
+{
+	register struct cstate *cs = comp->last_cs->cs_next;
+	register u_int hlen = ip->ip_hl;
+	register struct tcphdr *oth;
+	register struct tcphdr *th;
+	register u_int deltaS, deltaA;
+	register u_int changes = 0;
+	u_char new_seq[16];
+	register u_char *cp = new_seq;
+
+	/*
+	 * Bail if this is an IP fragment or if the TCP packet isn't
+	 * `compressible' (i.e., ACK isn't set or some other control bit is
+	 * set).  (We assume that the caller has already made sure the
+	 * packet is IP proto TCP).
+	 */
+	if ((ip->ip_off & htons(0x3fff)) || m->m_len < 40)
+		return (TYPE_IP);
+
+	th = (struct tcphdr *)&((int *)ip)[hlen];
+	if ((th->th_flags & (TH_SYN|TH_FIN|TH_RST|TH_ACK)) != TH_ACK)
+		return (TYPE_IP);
+	/*
+	 * Packet is compressible -- we're going to send either a
+	 * COMPRESSED_TCP or UNCOMPRESSED_TCP packet.  Either way we need
+	 * to locate (or create) the connection state.  Special case the
+	 * most recently used connection since it's most likely to be used
+	 * again & we don't have to do any reordering if it's used.
+	 */
+	INCR(sls_packets)
+	if (ip->ip_src.s_addr != cs->cs_ip.ip_src.s_addr ||
+	    ip->ip_dst.s_addr != cs->cs_ip.ip_dst.s_addr ||
+	    *(int *)th != ((int *)&cs->cs_ip)[cs->cs_ip.ip_hl]) {
+		/*
+		 * Wasn't the first -- search for it.
+		 *
+		 * States are kept in a circularly linked list with
+		 * last_cs pointing to the end of the list.  The
+		 * list is kept in lru order by moving a state to the
+		 * head of the list whenever it is referenced.  Since
+		 * the list is short and, empirically, the connection
+		 * we want is almost always near the front, we locate
+		 * states via linear search.  If we don't find a state
+		 * for the datagram, the oldest state is (re-)used.
+		 */
+		register struct cstate *lcs;
+		register struct cstate *lastcs = comp->last_cs;
+
+		do {
+			lcs = cs; cs = cs->cs_next;
+			INCR(sls_searches)
+			if (ip->ip_src.s_addr == cs->cs_ip.ip_src.s_addr
+			    && ip->ip_dst.s_addr == cs->cs_ip.ip_dst.s_addr
+			    && *(int *)th == ((int *)&cs->cs_ip)[cs->cs_ip.ip_hl])
+				goto found;
+		} while (cs != lastcs);
+
+		/*
+		 * Didn't find it -- re-use oldest cstate.  Send an
+		 * uncompressed packet that tells the other side what
+		 * connection number we're using for this conversation.
+		 * Note that since the state list is circular, the oldest
+		 * state points to the newest and we only need to set
+		 * last_cs to update the lru linkage.
+		 */
+		INCR(sls_misses)
+		comp->last_cs = lcs;
+		hlen += th->th_off;
+		hlen <<= 2;
+		if (hlen > m->m_len)
+			return (TYPE_IP);
+		goto uncompressed;
+
+	found:
+		/*
+		 * Found it -- move to the front on the connection list.
+		 */
+		if (cs == lastcs)
+			comp->last_cs = lcs;
+		else {
+			lcs->cs_next = cs->cs_next;
+			cs->cs_next = lastcs->cs_next;
+			lastcs->cs_next = cs;
+		}
+	}
+
+	/*
+	 * Make sure that only what we expect to change changed. The first
+	 * line of the `if' checks the IP protocol version, header length &
+	 * type of service.  The 2nd line checks the "Don't fragment" bit.
+	 * The 3rd line checks the time-to-live and protocol (the protocol
+	 * check is unnecessary but costless).  The 4th line checks the TCP
+	 * header length.  The 5th line checks IP options, if any.  The 6th
+	 * line checks TCP options, if any.  If any of these things are
+	 * different between the previous & current datagram, we send the
+	 * current datagram `uncompressed'.
+	 */
+	oth = (struct tcphdr *)&((int *)&cs->cs_ip)[hlen];
+	deltaS = hlen;
+	hlen += th->th_off;
+	hlen <<= 2;
+	if (hlen > m->m_len)
+		return (TYPE_IP);
+
+	if (((u_short *)ip)[0] != ((u_short *)&cs->cs_ip)[0] ||
+	    ((u_short *)ip)[3] != ((u_short *)&cs->cs_ip)[3] ||
+	    ((u_short *)ip)[4] != ((u_short *)&cs->cs_ip)[4] ||
+	    th->th_off != oth->th_off ||
+	    (deltaS > 5 &&
+	     BCMP(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) ||
+	    (th->th_off > 5 &&
+	     BCMP(th + 1, oth + 1, (th->th_off - 5) << 2)))
+		goto uncompressed;
+
+	/*
+	 * Figure out which of the changing fields changed.  The
+	 * receiver expects changes in the order: urgent, window,
+	 * ack, seq (the order minimizes the number of temporaries
+	 * needed in this section of code).
+	 */
+	if (th->th_flags & TH_URG) {
+		deltaS = ntohs(th->th_urp);
+		ENCODEZ(deltaS);
+		changes |= NEW_U;
+	} else if (th->th_urp != oth->th_urp)
+		/* argh! URG not set but urp changed -- a sensible
+		 * implementation should never do this but RFC793
+		 * doesn't prohibit the change so we have to deal
+		 * with it. */
+		 goto uncompressed;
+
+	if (deltaS = (u_short)(ntohs(th->th_win) - ntohs(oth->th_win))) {
+		ENCODE(deltaS);
+		changes |= NEW_W;
+	}
+
+	if (deltaA = ntohl(th->th_ack) - ntohl(oth->th_ack)) {
+		if (deltaA > 0xffff)
+			goto uncompressed;
+		ENCODE(deltaA);
+		changes |= NEW_A;
+	}
+
+	if (deltaS = ntohl(th->th_seq) - ntohl(oth->th_seq)) {
+		if (deltaS > 0xffff)
+			goto uncompressed;
+		ENCODE(deltaS);
+		changes |= NEW_S;
+	}
+
+	switch(changes) {
+
+	case 0:
+		/*
+		 * Nothing changed. If this packet contains data and the
+		 * last one didn't, this is probably a data packet following
+		 * an ack (normal on an interactive connection) and we send
+		 * it compressed.  Otherwise it's probably a retransmit,
+		 * retransmitted ack or window probe.  Send it uncompressed
+		 * in case the other side missed the compressed version.
+		 */
+		if (ip->ip_len != cs->cs_ip.ip_len &&
+		    ntohs(cs->cs_ip.ip_len) == hlen)
+			break;
+
+		/* (fall through) */
+
+	case SPECIAL_I:
+	case SPECIAL_D:
+		/*
+		 * actual changes match one of our special case encodings --
+		 * send packet uncompressed.
+		 */
+		goto uncompressed;
+
+	case NEW_S|NEW_A:
+		if (deltaS == deltaA &&
+		    deltaS == ntohs(cs->cs_ip.ip_len) - hlen) {
+			/* special case for echoed terminal traffic */
+			changes = SPECIAL_I;
+			cp = new_seq;
+		}
+		break;
+
+	case NEW_S:
+		if (deltaS == ntohs(cs->cs_ip.ip_len) - hlen) {
+			/* special case for data xfer */
+			changes = SPECIAL_D;
+			cp = new_seq;
+		}
+		break;
+	}
+
+	deltaS = ntohs(ip->ip_id) - ntohs(cs->cs_ip.ip_id);
+	if (deltaS != 1) {
+		ENCODEZ(deltaS);
+		changes |= NEW_I;
+	}
+	if (th->th_flags & TH_PUSH)
+		changes |= TCP_PUSH_BIT;
+	/*
+	 * Grab the cksum before we overwrite it below.  Then update our
+	 * state with this packet's header.
+	 */
+	deltaA = ntohs(th->th_sum);
+	BCOPY(ip, &cs->cs_ip, hlen);
+
+	/*
+	 * We want to use the original packet as our compressed packet.
+	 * (cp - new_seq) is the number of bytes we need for compressed
+	 * sequence numbers.  In addition we need one byte for the change
+	 * mask, one for the connection id and two for the tcp checksum.
+	 * So, (cp - new_seq) + 4 bytes of header are needed.  hlen is how
+	 * many bytes of the original packet to toss so subtract the two to
+	 * get the new packet size.
+	 */
+	deltaS = cp - new_seq;
+	cp = (u_char *)ip;
+	if (compress_cid == 0 || comp->last_xmit != cs->cs_id) {
+		comp->last_xmit = cs->cs_id;
+		hlen -= deltaS + 4;
+		cp += hlen;
+		*cp++ = changes | NEW_C;
+		*cp++ = cs->cs_id;
+	} else {
+		hlen -= deltaS + 3;
+		cp += hlen;
+		*cp++ = changes;
+	}
+	m->m_len -= hlen;
+	m->m_data += hlen;
+	*cp++ = deltaA >> 8;
+	*cp++ = deltaA;
+	BCOPY(new_seq, cp, deltaS);
+	INCR(sls_compressed)
+	return (TYPE_COMPRESSED_TCP);
+
+	/*
+	 * Update connection state cs & send uncompressed packet ('uncompressed'
+	 * means a regular ip/tcp packet but with the 'conversation id' we hope
+	 * to use on future compressed packets in the protocol field).
+	 */
+uncompressed:
+	BCOPY(ip, &cs->cs_ip, hlen);
+	ip->ip_p = cs->cs_id;
+	comp->last_xmit = cs->cs_id;
+	return (TYPE_UNCOMPRESSED_TCP);
+}
+
+
+int
+sl_uncompress_tcp(bufp, len, type, comp)
+	u_char **bufp;
+	int len;
+	u_int type;
+	struct slcompress *comp;
+{
+	return sl_uncompress_tcp_part(bufp, len, len, type, comp);
+}
+
+
+/*
+ * Uncompress a packet of total length total_len.  The first buflen
+ * bytes are at *bufp; this must include the entire (compressed or
+ * uncompressed) TCP/IP header.  In addition, there must be enough
+ * clear space before *bufp to build a full-length TCP/IP header.
+ */
+int
+sl_uncompress_tcp_part(bufp, buflen, total_len, type, comp)
+	u_char **bufp;
+	int buflen, total_len;
+	u_int type;
+	struct slcompress *comp;
+{
+	register u_char *cp;
+	register u_int hlen, changes;
+	register struct tcphdr *th;
+	register struct cstate *cs;
+	register struct ip *ip;
+
+	switch (type) {
+
+	case TYPE_UNCOMPRESSED_TCP:
+		ip = (struct ip *) *bufp;
+		if (ip->ip_p >= MAX_STATES)
+			goto bad;
+		cs = &comp->rstate[comp->last_recv = ip->ip_p];
+		comp->flags &=~ SLF_TOSS;
+		ip->ip_p = IPPROTO_TCP;
+		hlen = ip->ip_hl;
+		hlen += ((struct tcphdr *)&((int *)ip)[hlen])->th_off;
+		hlen <<= 2;
+		BCOPY(ip, &cs->cs_ip, hlen);
+		cs->cs_ip.ip_sum = 0;
+		cs->cs_hlen = hlen;
+		INCR(sls_uncompressedin)
+		return (total_len);
+
+	default:
+		goto bad;
+
+	case TYPE_COMPRESSED_TCP:
+		break;
+	}
+	/* We've got a compressed packet. */
+	INCR(sls_compressedin)
+	cp = *bufp;
+	changes = *cp++;
+	if (changes & NEW_C) {
+		/* Make sure the state index is in range, then grab the state.
+		 * If we have a good state index, clear the 'discard' flag. */
+		if (*cp >= MAX_STATES)
+			goto bad;
+
+		comp->flags &=~ SLF_TOSS;
+		comp->last_recv = *cp++;
+	} else {
+		/* this packet has an implicit state index.  If we've
+		 * had a line error since the last time we got an
+		 * explicit state index, we have to toss the packet. */
+		if (comp->flags & SLF_TOSS) {
+			INCR(sls_tossed)
+			return (0);
+		}
+	}
+	cs = &comp->rstate[comp->last_recv];
+	hlen = cs->cs_ip.ip_hl << 2;
+	th = (struct tcphdr *)&((u_char *)&cs->cs_ip)[hlen];
+	th->th_sum = htons((*cp << 8) | cp[1]);
+	cp += 2;
+	if (changes & TCP_PUSH_BIT)
+		th->th_flags |= TH_PUSH;
+	else
+		th->th_flags &=~ TH_PUSH;
+
+	switch (changes & SPECIALS_MASK) {
+	case SPECIAL_I:
+		{
+		register u_int i = ntohs(cs->cs_ip.ip_len) - cs->cs_hlen;
+		th->th_ack = htonl(ntohl(th->th_ack) + i);
+		th->th_seq = htonl(ntohl(th->th_seq) + i);
+		}
+		break;
+
+	case SPECIAL_D:
+		th->th_seq = htonl(ntohl(th->th_seq) + ntohs(cs->cs_ip.ip_len)
+				   - cs->cs_hlen);
+		break;
+
+	default:
+		if (changes & NEW_U) {
+			th->th_flags |= TH_URG;
+			DECODEU(th->th_urp)
+		} else
+			th->th_flags &=~ TH_URG;
+		if (changes & NEW_W)
+			DECODES(th->th_win)
+		if (changes & NEW_A)
+			DECODEL(th->th_ack)
+		if (changes & NEW_S)
+			DECODEL(th->th_seq)
+		break;
+	}
+	if (changes & NEW_I) {
+		DECODES(cs->cs_ip.ip_id)
+	} else
+		cs->cs_ip.ip_id = htons(ntohs(cs->cs_ip.ip_id) + 1);
+
+	/*
+	 * At this point, cp points to the first byte of data in the
+	 * packet.  If we're not aligned on a 4-byte boundary, copy the
+	 * data down so the ip & tcp headers will be aligned.  Then back up
+	 * cp by the tcp/ip header length to make room for the reconstructed
+	 * header (we assume the packet we were handed has enough space to
+	 * prepend 128 bytes of header).  Adjust the length to account for
+	 * the new header & fill in the IP total length.
+	 */
+	buflen -= (cp - *bufp);
+	total_len -= (cp - *bufp);
+	if (buflen < 0)
+		/* we must have dropped some characters (crc should detect
+		 * this but the old slip framing won't) */
+		goto bad;
+
+	if ((int)cp & 3) {
+		if (buflen > 0)
+			(void) ovbcopy(cp, (caddr_t)((int)cp &~ 3), buflen);
+		cp = (u_char *)((int)cp &~ 3);
+	}
+	cp -= cs->cs_hlen;
+	total_len += cs->cs_hlen;
+	cs->cs_ip.ip_len = htons(total_len);
+	BCOPY(&cs->cs_ip, cp, cs->cs_hlen);
+	*bufp = cp;
+
+	/* recompute the ip header checksum */
+	{
+		register u_short *bp = (u_short *)cp;
+		for (changes = 0; hlen > 0; hlen -= 2)
+			changes += *bp++;
+		changes = (changes & 0xffff) + (changes >> 16);
+		changes = (changes & 0xffff) + (changes >> 16);
+		((struct ip *)cp)->ip_sum = ~ changes;
+	}
+	return (total_len);
+bad:
+	comp->flags |= SLF_TOSS;
+	INCR(sls_errorin)
+	return (0);
+}
diff --git a/sys/net/pppcompress.h b/sys/net/pppcompress.h
new file mode 100644
index 0000000..b73be42
--- /dev/null
+++ b/sys/net/pppcompress.h
@@ -0,0 +1,170 @@
+/*
+ * Definitions for tcp compression routines.
+ *
+ * Copyright (c) 1989 Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
+ *	- Initial distribution.
+ *
+ *	Paul Mackerras (paulus@cs.anu.edu.au), June 1993:
+ *	- added sl_uncompress_tcp_part.
+ *
+ *	From: 	slcompress.h	7.4	90/06/28
+ *	$Id: slcompress.h,v 1.5 1994/01/15 20:13:16 deraadt Exp $
+ */
+
+#ifndef _SLCOMPRESS_H_
+#define _SLCOMPRESS_H_
+
+#define MAX_STATES 16		/* must be > 2 and < 256 */
+#define MAX_HDR MLEN		/* XXX 4bsd-ism: should really be 128 */
+
+/*
+ * Compressed packet format:
+ *
+ * The first octet contains the packet type (top 3 bits), TCP
+ * 'push' bit, and flags that indicate which of the 4 TCP sequence
+ * numbers have changed (bottom 5 bits).  The next octet is a
+ * conversation number that associates a saved IP/TCP header with
+ * the compressed packet.  The next two octets are the TCP checksum
+ * from the original datagram.  The next 0 to 15 octets are
+ * sequence number changes, one change per bit set in the header
+ * (there may be no changes and there are two special cases where
+ * the receiver implicitly knows what changed -- see below).
+ * 
+ * There are 5 numbers which can change (they are always inserted
+ * in the following order): TCP urgent pointer, window,
+ * acknowlegement, sequence number and IP ID.  (The urgent pointer
+ * is different from the others in that its value is sent, not the
+ * change in value.)  Since typical use of SLIP links is biased
+ * toward small packets (see comments on MTU/MSS below), changes
+ * use a variable length coding with one octet for numbers in the
+ * range 1 - 255 and 3 octets (0, MSB, LSB) for numbers in the
+ * range 256 - 65535 or 0.  (If the change in sequence number or
+ * ack is more than 65535, an uncompressed packet is sent.)
+ */
+
+/*
+ * Packet types (must not conflict with IP protocol version)
+ *
+ * The top nibble of the first octet is the packet type.  There are
+ * three possible types: IP (not proto TCP or tcp with one of the
+ * control flags set); uncompressed TCP (a normal IP/TCP packet but
+ * with the 8-bit protocol field replaced by an 8-bit connection id --
+ * this type of packet syncs the sender & receiver); and compressed
+ * TCP (described above).
+ *
+ * LSB of 4-bit field is TCP "PUSH" bit (a worthless anachronism) and
+ * is logically part of the 4-bit "changes" field that follows.  Top
+ * three bits are actual packet type.  For backward compatibility
+ * and in the interest of conserving bits, numbers are chosen so the
+ * IP protocol version number (4) which normally appears in this nibble
+ * means "IP packet".
+ */
+
+/* packet types */
+#define TYPE_IP 0x40
+#define TYPE_UNCOMPRESSED_TCP 0x70
+#define TYPE_COMPRESSED_TCP 0x80
+#define TYPE_ERROR 0x00
+
+/* Bits in first octet of compressed packet */
+#define NEW_C	0x40	/* flag bits for what changed in a packet */
+#define NEW_I	0x20
+#define NEW_S	0x08
+#define NEW_A	0x04
+#define NEW_W	0x02
+#define NEW_U	0x01
+
+/* reserved, special-case values of above */
+#define SPECIAL_I (NEW_S|NEW_W|NEW_U)		/* echoed interactive traffic */
+#define SPECIAL_D (NEW_S|NEW_A|NEW_W|NEW_U)	/* unidirectional data */
+#define SPECIALS_MASK (NEW_S|NEW_A|NEW_W|NEW_U)
+
+#define TCP_PUSH_BIT 0x10
+
+
+/*
+ * "state" data for each active tcp conversation on the wire.  This is
+ * basically a copy of the entire IP/TCP header from the last packet
+ * we saw from the conversation together with a small identifier
+ * the transmit & receive ends of the line use to locate saved header.
+ */
+struct cstate {
+	struct cstate *cs_next;	/* next most recently used cstate (xmit only) */
+	u_short cs_hlen;	/* size of hdr (receive only) */
+	u_char cs_id;		/* connection # associated with this state */
+	u_char cs_filler;
+	union {
+		char csu_hdr[MAX_HDR];
+		struct ip csu_ip;	/* ip/tcp hdr from most recent packet */
+	} slcs_u;
+};
+#define cs_ip slcs_u.csu_ip
+#define cs_hdr slcs_u.csu_hdr
+
+/*
+ * all the state data for one serial line (we need one of these
+ * per line).
+ */
+struct slcompress {
+	struct cstate *last_cs;	/* most recently used tstate */
+	u_char last_recv;	/* last rcvd conn. id */
+	u_char last_xmit;	/* last sent conn. id */
+	u_short flags;
+#ifndef SL_NO_STATS
+	int sls_packets;	/* outbound packets */
+	int sls_compressed;	/* outbound compressed packets */
+	int sls_searches;	/* searches for connection state */
+	int sls_misses;		/* times couldn't find conn. state */
+	int sls_uncompressedin;	/* inbound uncompressed packets */
+	int sls_compressedin;	/* inbound compressed packets */
+	int sls_errorin;	/* inbound unknown type packets */
+	int sls_tossed;		/* inbound packets tossed because of error */
+#endif
+	struct cstate tstate[MAX_STATES];	/* xmit connection states */
+	struct cstate rstate[MAX_STATES];	/* receive connection states */
+};
+/* flag values */
+#define SLF_TOSS 1		/* tossing rcvd frames because of input err */
+
+extern void sl_compress_init __P((struct slcompress *));
+extern void sl_compress_setup __P((struct slcompress *, int maxslot));
+extern u_char sl_compress_tcp __P((struct mbuf *m, struct ip *ip,
+				   struct slcompress *, int comp_cid_flag));
+extern int sl_uncompress_tcp __P((u_char **bufp, int len, u_int type,
+				  struct slcompress *));
+extern int sl_uncompress_tcp_part __P((u_char **bufp, int buflen,
+				       int total_len, u_int type,
+				       struct slcompress *));
+
+#endif /* _SLCOMPRESS_H_ */